The present invention relates to a unit and method for feeding semifinished parts on to a forming machine, particularly a press.
More specifically, the present invention relates to a continuous, slidefree feed unit for stacked, possibly preshaped, sheet metal blanks.
Most units for continuously feeding stacked blanks on to a press comprise a pickoff device, a blank locating device, and a robot handling fixture for transferring the blank from the locating device on to the press.
The pickoff device normally comprises two or more pairs of magnets usually located along the edge of the blanks stacked in a loading station, and which cooperate with a robot handling fixture for transferring the blank on to the locating device.
Though widely used and satisfactory from the operating standpoint, known feed units of the aforementioned type present several drawbacks.
Foremost of these is the size of the unit, which only enables it to be employed for feeding isolated presses, or on-line presses for which relatively ample floor space is provided in front of the press. Secondly, stations of the type briefly described above involve relatively high construction and running costs, by virtue of featuring at least two robot handling fixtures between the devices on the unit, and as many control systems for enabling dialoging between the robot fixtures and devices.
Thirdly, the flexibility of such stations is invariably poor, especially as regards automatic adjustment to changes in the configuration and location of the stack at the loading station. In most cases, in fact, no sensors are provided for detecting, for example, lateral shifting of the stack from the vertical position during transport, or mutual shifting of the blanks within the stack itself. As such, stations of the aforementioned type require the full-time attendance of one or more control operators, as well as auxiliary stacking devices, thus further increasing the cost of the unit.